1. Field of the Invention
This invention relates to an information storage stamper used for making magnetic disks, optical disks and magneto-optic disks capable of effecting a high-density storage and to a method of manufacturing information storage disks using the same.
2. Description of The Prior Art
One of most important points required for optical disks or magnetic disks is to ensure that date can be reliably stored for a long period of time and that high-speed writing and reading of data can be made stably and reliably in such disks. For this, it is necessary to use an undeformable one as a disk material and preferable to use glass or aluminium (Al). For example, when glass is used as a disk material, it is conventionally general to form guide grooves on a disk by photopolymer method. (See, for example, H. Kanamaru, "Optical Video-Disk System", the Journal of the Institute of Television Engineers of Japan, Vol. 32, No. 1, p.15, 1978).
With the system above referred to, optical disk stampers use a stamper made of nickel, resulting in a low heat resistance. Therefore, it is generally impossible to transfer guide grooves directly to a highly heat-resistant disk made of glass, aluminium or the like. In addition, recently, such a method that guide grooves are formed directly on a glass disk by further improved reactive ion etching method has been also developed. (See, for example, K. Ota, et al., "Vaccum", 28 (2), 77, 1985.)
Processes for forming guide grooves on a typical glass disk will be explained below. After a glass disk has been cleaned, a positive type resist is coated thereon up to a thickness of 200 to 300 nm using a spin coater. After prebaked, an argon laser beam is condensed and the laser beam thus condensed is moved, while the disk is being rotated at a constant speed, in the radial direction of the disk. Thus, a spiral guide groove having a groove width of about 0.8 .mu.m and a pitch of 1.6 .mu.m is recorded on the disk. Then, the spiral guide groove is developed and the reactive ion etching is applied thereto with the remaining resist as a mask in the CHF.sub.3 gas atmosphere. After the glass disk has been etched up to a depth of about 70 nm, unnecessary resist is made into ashes using oxygen for removal, thus being capable of forming guide grooves on the surface of a glass disk for optical use. This method does not use a stamper, resulting in a low productivity. In addition, magnetic disks generally have no guide groove as with optical disks, which means that the magnetic disks lag behind the optical ones in high track densification.